ROV friendly vortex induced vibration inhibitor and method of use

ABSTRACT

The present invention discloses a vortex induced vibration inhibitor (“VIVI”) comprising a hollow cylindrical housing having an elongated opening defined by locking edges. The housing is operable between an open and a closed position. Connecting assemblies include barbed connector pins received in grooved housings. Connector slots are provided in the connector and receptor housings. Retainer pins provide for release of connecting assemblies. Spacers are provided to limit movement of the housing in relation to the surrounded structure. An alignment stub is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/627,408 entitled, “ROV Friendly Vortex InducedVibration Inhibitor,” filed Nov. 12, 2004 in the United States Patentand Trademark Office and to International Application NumberPCT/US2005/041137 entitled, “ROV Friendly Vortex Induced VibrationInhibitor,” filed Nov. 14, 2005 with the United States Patent andTrademark Receiving Office.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reduction of vortex-induced vibrationson submerged cylindrical pipelines, risers, and tendons. Specifically,this invention relates to the vortex induced vibration inhibitorsinstalled on submerged cylindrical pipelines, risers, and tendons.

2. Description of the Related Art

Submerged cylindrical pipelines, risers, and tendons are subjected tovibrations caused by the periodic shedding of eddies resulting fromfluid flow. The vibrations place additional stress on the pipelines,risers, and tendons and reduce their fatigue lives. Vortex inducedvibration inhibitors (VIVIs) are installed onto the vibration sensitivecomponents to eliminate the effects of vortex-induced vibrations.

Strakes are cylindrically shaped housings with fixed fins helicallyattached to the outer surface. Typically, but not always, strakes areinstalled on risers, pipelines, and tendons along the sections close tothe water's surface where both current and wave forces are encountered.

Fairings have a streamlined (sometimes tear-dropped) cross-sectionalshape and include a bearing surface so that they rotate around theriser, pipeline or tendon with the direction of current flow. Typically,fairings are used at depths well below the surface so that wave forcesdo not cause premature wear of the rotational bearing pads.

Many deepwater offshore platforms and many floating platforms have beeninstalled without VIVIs. It was learned that ocean currents inducedvibrations in platform support structures. The solution to eliminatingvortex-induced vibrations on existing structures is to add fixed-finvortex strakes or fairings to the long cylindrical components of thesestructures. In light of more recent findings showing that ocean currentsare much stronger than originally thought, retrofitting existingstructures with VIVIs is desirable.

The preferred method of retrofitting existing risers, pipelines, andtendons with VIVIs is to utilize a remotely operable vehicle (ROV). AnROV is an underwater robot that is typically controlled from thesurface. The ROV may be equipped with hydraulic manipulators, or arms,to assist in performing subsea tasks, and with special tooling toinstall VIVIs onto underwater structures.

To prepare prior art VIVIs for installation by an ROV, the VIVIs areretrofitted with hardware, such as handles and ropes. Severalretrofitted VIVIs may be placed onto a piece of staging equipment thatis lowered to an area proximate the submerged component or theretrofitted VIVI may be lowered individually by a crane. An ROV,equipped with arms, grasps one VIVI at a time and transports it to asubmerged cylindrical component.

A vision system and a remote control system allow an operator tomaneuver the ROV to the staging area and remove the VIVI. Once thesubmerged component is nested within the VIVI, the ROV disengages fromthe VIVI and maneuvers to the opposite side of the VIVI and component.The ROV operator then uses the vision system to locate handles or ropesand grasp them with tooling on the ROV arms. The arms may then be movedto close the VIVI around the submerged component.

Prior art VIVIs are often destroyed when they are forcibly removed.Further, the VIVI often damages the coating on the submerged componentsas they are removed. It would be an improvement to the art to have areleasable locking mechanism that permits the removal of a VIVI withoutdamaging either the VIVI or the coating of the submerged component.

It would be a further improvement to the art to have engagement pointsthat permit the use of simple tooling on the ROV to engage and installthe VIVIs around a submerged component.

It would be a further improvement to the art to have engagement pointsthat permit the use of simple tooling on the ROV to engage and installthe around a submerged component.

It would be a further improvement of the art to have a system wheremultiple VIVI's may be efficiently installed around a submergedcomponent.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide adevice for reducing the vortex vibrations caused by water current.

It is another object of the present invention to provide a connectorassembly to interface between an ROV and a VIVI.

It is another object of the present invention to provide connectorassemblies that are integral with the surface of the VIVI.

It is another object of the present invention to provide connectorassemblies that allow for efficient and quick engagement anddisengagement between an ROV and a VIVI.

It is another object of the present invention to provide a connectorassembly that permits maneuverability of a VIVI by an ROV.

It is another object of the present invention to provide a connector inwhich an ROV need only engage with a VIVI a single time to move it to asubmerged component, place the VIVI around the component and lock theVIVI in place around the submerged component.

It is another object of the present invention to provide a releasablelocking mechanism permitting the VIVI to be removed from a submergedcomponent without damaging the VIVI or submerged component, therebymaking the VIVI reusable.

It is another object of the invention to provide a flexible VIVI.

It is another object of the invention to provide a VIVI front housingand pivot sections as a unitary structure.

It is another object of the invention to induce frictional interactionbetween the VIVI and the submerged component.

The present invention discloses a ROV friendly vortex induced vibrationinhibitor (“VIVI”) for installation on a subsea structure, such as ariser or pipeline. The VIVI eliminates the effects of vortex-inducedvibrations on the cylindrical structure. The VIVI includes a housing,connector assemblies, fins, a plurality of annulus spacers, and analignment stub. The housing is cylindrically formed and preferablyconstructed of a flexible material, such as high-density polyethylene.One or more fins are formed or attached helically around the outersurface of the housing along the longitudinal length. An alignment stubextends outwardly from the housing and is an engagement member for anROV tool. A plurality of connector assemblies permit secured closure ofthe housing and provide additional engagement points for the ROV tool.The connector assemblies are removable, thereby allowing subsequentremoval of the VIVI from the cylindrical structure without causingdamage to the connector assemblies, the housing, or the cylindricalstructure. A plurality of annulus spacers are provided along the housingto induce friction between the VIVI and the cylindrical structure.

Other features and advantages of the invention will be apparent from thefollowing description, the accompanying drawing and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of the preferred embodiment of the VIVI of thepresent invention.

FIG. 2 is a side view of the preferred embodiment of the VIVI of thepresent invention.

FIG. 3 a is an end view of the preferred embodiment of the VIVI of thepresent invention with the wings in a closed position.

FIG. 3 b is a cut away end view of the preferred embodiment of the VIVIof the present invention with the wings in an open position.

FIG. 4 is a side view of an alignment stub.

FIG. 5 is an end view of the preferred embodiment of a connectorreceptor.

FIG. 6 a is a cross-sectional side view of the preferred embodiment of aconnector receptor.

FIG. 6 b is an isometric view of the preferred embodiment of a connectorreceptor sleeve.

FIG. 7 a is a side view of the preferred embodiment of a connectorinsert.

FIG. 7 b is a top view of the preferred embodiment of a connector pin.

FIG. 8 is a view of an annulus spacer.

FIG. 9 is a perspective of an alternative VIVI with an alternativeconnector assembly.

FIG. 10 a is a cross-sectional view of an alternative VIVI in the closedposition.

FIG. 10 b is a cross-sectional view of an alternative VIVI in the openposition.

FIG. 11 is a cross-sectional view of an alternative connector assembly.

FIG. 12 is an end view of an alternative connector base.

FIG. 13 is a side view of an alternative receptor assembly.

FIG. 14 is a side view of an alternative insert assembly.

DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, the preferred embodiment of a vortex inducedvibration inhibitor (“VIVI”) 100 for installation by a remotely operablevehicle (ROV) (not shown) is depicted. VIVI 100 includes connectorassemblies 140 for the installation of VIVI 100 on a submerged componentby an ROV, fins 220 and an alignment stub 110.

Referring to FIGS. 1, 2 and 3 a and 3 b, VIVI 100 comprises a housing210 and at least one fin 220. Housing 210 is cylindrically shaped withan inner diameter 212 and an outer diameter 214. Inner diameter 212accommodates an elongated, usually cylindrical, structure 500 (depictedwith dashed line in FIG. 3), such as a riser, tendon, or pipeline.Housing 210 has a housing axis 204 and structure 500 has a structureaxis 504. Housing axis 204 and structure axis 504 are coaxially aligned.

As depicted in FIGS. 3 a and 3 b, housing 210 extends from a firstlocking edge 232 to a second locking edge 234. When housing 210 is in aclosed position, first locking edge 232 and second locking edge 234abut.

In the preferred embodiment, housing 210 is constructed of a flexiblematerial, such as high-density polyethylene. High-density polyethyleneis preferred due to its density, which aids in housing 210 achievingneutral buoyancy, and due to its flexibility, enabling VIVI 100 toflexibly open and receive structure 500.

In the preferred embodiment of the invention, housing 210 is a unitarilyformed cylindrical structure. One or more fins 220 are formed orattached helically around the outer surface 216 of housing 210 along thelongitudinal length 218. The number of fins 220 most effective forreducing eddy formation is determined by the outer diameter of thestructure 500 on which VIVI 100 is installed.

Referring to the preferred embodiment depicted in FIGS. 2, 3 a, 3 b and4, alignment stub 110 extends outwardly from front housing 250 and is anengagement member for an ROV tool (not shown). Alignment stub 110 has analignment stub body 112. In the embodiment depicted, stub body 112 iscylindrical. A top surface 114 having a top width 116 is provided distalhousing 210. Preferably, strake housing 210 and alignment stub 110 areintegrally formed such that stub 110 is an extension of housing 210.

The shape of alignment stub body 112 and the size of top surface 114 aredetermined by the tooling on the ROV. Top surface 114 may be tapered toaid in the engagement of alignment stub 110 by the ROV engagement tool.

Preferably, alignment stub 110 is centrally located on front housing250. By locating alignment stub 110 at a central point bothlongitudinally and laterally on front housing 250, the weight of theVIVI 100 will be evenly distributed when VIVI 100 is engaged at stub110. This even weight distribution aids in manipulation of VIVI 100 byan ROV.

Alignment key 120 allows rotational control of VIVI 100 by the ROV.Alignment key 120, in the embodiment depicted, comprises a channelextending across upper surface 114 of stub 110. The geometry ofalignment key 120 is determined by the tooling on the ROV. A variety ofalignment key 120 geometries are contemplated being either formed intoor extending from top surface 114, including channels of a determinedgeometry in upper surface 114 or extensions of a determined geometryextending outwardly from upper surface 114.

A stub grip 130 provides a grasping surface for the ROV manipulationtool to firmly grasp the VIVI 100. Stub grip 130 is formed intoalignment stub body 112 and is located intermediate top surface 114 andfront housing 250. In the embodiment depicted, stub grip 130 comprises achannel extending laterally around stub body 112. A variety of stub grip130 geometries are contemplated being either formed into or extendingfrom stub body 112, including channels of a determined geometry in stubbody 112 or extensions of a determined geometry extending outwardly fromstub body 112.

A different configuration of alignment stub 110 may be utilized toconform to determined ROV grasping tooling.

Housing 210 is susceptible to rotational and axial movement in relationto structure 500. To limit rotational and axial movement, annulusspacers 280 are installed along inner surface 215 of housing 210.

Inner diameter 212 accommodates annulus spacers 280. Referring to FIG.8, annulus spacer 280 has an inner spacer member 282, a spacer recess286, and a spacer retainer 288. Inner spacer member 282 has a spacermember diameter 281, which is larger than the diameter of spacer hole285. Spacer recess 286 has a recess diameter 283. Recess diameter 283 issized to be equal to or smaller than the diameter of spacer hole 285.Spacer retainer 288 comprises a truncated cone having a retainer basediameter 289 and a retainer head diameter 287. Retainer head diameter287 is preferably smaller than retainer base diameter 289. Retainer headdiameter 287 is also preferably smaller than the diameter of spacer hole285, while retainer base diameter 289 is preferably larger than thediameter of spacer hole 285. This configuration allows spacer retainer288 to be readily installed by inserting into spacer hole 285.

Each spacer 280 is inserted through spacer hole 285 in housing 210 frominner surface 215, wherein retainer head tip 290 is aligned with spacerhole 285, and a determined force is asserted against spacer surface 284until retainer base 291 passes through spacer hole 285 and retainer base291 abuts the exterior surface 216 of housing 210. Therefore, wheninstalled, spacer recess 286 is aligned with housing 210, and innerspacer member 282 abuts interior surface 215 of housing 210. Innerspacer member 282 is preferably configured and sized such that it cannotbe deformed to pass through spacer hole 285. Spacer retainer 288 issufficiently flexible that it may be elastically deformed to passthrough spacer hole 285.

Annulus spacers 280 are sized such that inner spacer member 282 abutsouter surface 502 of structure 500 when VIVI 100 is installed onstructure 500. In the preferred embodiment, spacer surface 284 isconcave, preferably contouring outer surface 216 of housing 210. Thisconfiguration provides a suction effect between spacer surface 284 andstructure 500. While frictional spacer surface 284 is preferablyconcave, other configurations are possible (not shown).

Annulus spacers 280 are constructed of material suitable to inducefrictional interaction between housing 210 and structure 500. In atypical application commercially available, 70-80 shore urethane ispracticed. When VIVI 100 is installed on structure 500, annulus spacers280 collectively reduce relative rotational and axial movement ofhousing 210 in relation to structure 500 by hoop stress and frictionalresistance to movement. Further, annulus spacers 280 maintain a gapbetween housing 210 and structure 500, thereby allowing water flowbetween housing 210 and structure 500.

Referring to FIGS. 1, 2, 3 a, and 3 b, a plurality of connectorassemblies 140 are located proximate first and second locking edges 232and 234, thereby permitting connection of first locking edge 232 tosecond locking edge 234. Housing 210 is depicted in a closed position inFIG. 3 a, and in an open position in FIG. 3 b.

Each connector assembly 140 comprises a connector insert assembly 158and a connector receptor assembly 148. Connector insert assembly 158 isattached to a connector base 166 proximate first locking edge 232.Connector receptor assembly 148 is attached to a connector base 166proximate second locking edge 234. Insert assembly 158 and receptorassembly 148 are aligned so that connector pin 170 is received inreceptor 172 when housing 210 is in a closed position, as depicted inFIGS. 1 and 3 a.

In a preferred embodiment, at least two sets of connector assemblies 140are provided on each VIVI 100. Each connector assembly 140 isintermediate alignment stub 110 and an end of vIvI 100.

Referring to FIGS. 6 b and 7 b, connector receptor 172 comprisesreceptor segments 182 and 184, and receptor retaining sleeve 186.Receptor segments 182 and 184, when connected, comprise a hollowcylinder. Receptor retaining sleeve 186 holds receptor segments 182 and184 in a joined position. Receptor retaining sleeve 186 covers at leasta portion of the exterior surfaces of receptor segments 182 and 184. Inthe preferred embodiment, receptor retaining sleeve 186 slidingly fitsover grooved ends 188 and 189 of segments 182 and 184. Holes 180 areprovided in segments 182 and 184 distal grooved ends 188 and 190 forinsertion of a retainer pin 167.

A plurality of grooves 194 are provided on the interior surfaces ofsegments 182 and 184 proximate grooved ends 188 and 189. Receptor 172,grooves 194, connector pin 170 and barbs 174 are so sized in relation toeach other that connector pin 170 may be inserted into receptor 172 by adetermine pushing force. Once inserted, barbs 174 and grooves 194interlock to prevent removal of connector pin 170 from receptor 172without application of a determined pulling force. Each barb 174 isprovided with an inclined front face 175 and a rear face 179perpendicular to axis 171 of connector pin 170, thereby allowing the pin170 to be inserted among grooves 194 of receptor 172 with less forcethan the force required to pull pin 170 from receptor 172.

Referring to FIGS. 5, 6 a and 6 b, the arrangement of receptor 172 withconnector base 166 is depicted. Connector base 166 includes a basehousing 165 having side walls 150 and 152, front wall 153, top 155 andrear wall 157. In the preferred embodiment, base housing 165 is integralwith one of locking edge 232 or 234. In an alternate embodiment, basehousing 165 is distinct from first locking edge 232 or second lockingedge 234, but attached to one of locking edge 232 or 234.

Side walls 150 and 152 of base housing 165 extend outwardly from basehousing 165 past rear wall 157. Side walls 150 and 152 are parallel andspaced from each other. Engagement slots 160 are provided in each ofside walls 150 and 152. Engagement slots 160 are sized and structured toallow an ROV manipulator tool (not shown), such as a solenoid-operatedrod to extend therethrough.

A front wall opening 159 is provided in the front wall 153. A rear wallopening 161 is provided in rear wall 157. Front wall opening 159 andrear wall opening 161 are aligned to allow receptor 172 segments 182 and184 to extend through front wall opening 159 and rear wall opening 161and thus through base housing 155. Upon installation of receptor 172into connector base 166, a retainer pin 167 may be inserted throughaligned holes 180. A flange 169 extends outwardly from receptor 172intermediate grooved ends 188 and 190 and holes 180. Receptor 172, basehousing 165 and holes 180 are so structured and aligned that receptor172 is fixedly retained on connector base 166 with base housing 165intermediate flange 169 and retainer pin 167.

Pin 167 has a grasping loop 173 extending outwardly from pin 167 andbase housing 165 to allow removal of pin 167 by an ROV manipulator tool(not shown). Retainer pin 167 is configured to prevent retainer pin 167from dislodging when subjected to prolonged vibration. While a cotterpin is depicted in the preferred embodiment, other pin retainingstructures may be utilized.

Referring to FIG. 7 b, connector pin 170 comprises an elongatedcylindrical member having a plurality of barbs 174 extending outwardlyfrom insert end 176. Insert end 176 has a conical insert tip 178.Conical insert tip 178 enhances fitting of insert end 176 into receptor172. Connector pin 170 is further provided with a hole 180 distal insertend 176 for insertion of a retainer pin 167.

Referring to FIGS. 7 a and 7 b, the arrangement of connector pin 170with connector base 166 is depicted. Connector pin 170 is provided withan outwardly-extending flange 177 intermediate barbs 174 and pin opening180. Connector pin 170 is inserted through front wall 153 and throughrear wall 157. Upon installation of connector pin 170 into base housing165, a retainer pin 167 may be inserted through hole 180. Connector pin170, base housing 166 and holes 180 are so structured and aligned thatconnector pin 170 is fixedly retained on connector base 166 with basehousing 165 intermediate retainer pin 167 and flange 177. A washer maybe used intermediate retainer pin 167 and base housing 165 to preventwear of the retainer pin 167 on base housing 165.

Referring to FIGS. 5, 7 a and 7 b, connector pin 170 is provided with anoutwardly-extending flange 177 intermediate barbs 174 and pin opening180. Connector pin 170 is inserted through front wall 153 and throughrear wall 157. Upon installation of connector pin 170 into base housing165, a retainer pin 167 may be inserted through hole 180. Connector pin170, base housing 166 and holes 180 are so structured and aligned thatconnector pin 170 is fixedly retained on connector base 166 with basehousing 165 intermediate retainer pin 167 and flange 177. A washer (notshown) may be used intermediate retainer pin 167 and base housing 165 toprevent wear of the retainer pin 167 on base housing 165.

In the preferred embodiment, at least one VIVI 100 is attached to atransporting device (not shown). The VIVI is then submerged into a bodyof water and transported to the point of installation.

As previously described, VIVI 100 is constructed for use with an ROVhaving manipulator tooling installed on a plurality of arms. Alignmentstub grip 130 and alignment key 120 allow the ROV to readily engage VIVI100. Alignment stub grip 130 allows a fixed lateral position andalignment key 120 allows the VIVI 100 to be rotated about stub 110. AnROV engagement tool engages alignment stub 110 of a predetermined VIVI100. Two spaced ROV arms have manipulator tools to engage withengagement slots 160 of connector assemblies 140. Once the ROV is fullyengaged with VIVI 100, the ROV disengages VIVI 100 from a deploymentframe (not shown). The ROV then propels VIVI 100 toward structure 500.The ROV engagement tool then disengages alignment stub 110, with the ROVarms remaining engaged with engagement slots 160. Once alignment stub110 has been disengaged, the ROV arms may rotate housing 210 into anopen position. The ROV arms should rotate housing 210 open untillongitudinal opening 230 is sufficiently spaced for receiving structure500. The ROV engagement tool is disengaged from the alignment stub 110prior to rotating housing 210 to the open position to limit stress onhousing 210.

Once housing 210 has been rotated into an open position, the ROV engagesVIVI 100 with structure 500. The ROV arms then rotate housing 210 to aclosed position, thereby inserting connector pin 170 into connectorreceptor 172. The tapered end 178 of connector pin 170 facilitates entryof connector pin 170 into receptor 172. Upon successful attachment ofVIVI 100, the ROV tooling releases from VIVI 100 by disengaging itsmanipulator tools from engagement slots 160.

After installation, connector insert 170 is held within connectorreceptor 172. If it is subsequently necessary to remove VIVI 100 fromthe structure 500, an ROV with appropriate manipulator arm tooling or adiver can remove one of the retainer pins 167 from the connectorreceptor 172 of each connector assembly 140. Upon removal of retainerpin 167, the connector receptor 172 retained by such retainer pin 167may be disengaged from the connector base 166 while connector insert 170remains connected to connector base 166. Alternatively, the ROV canremove the retainer pin 167 from the connector insert 170, leavingconnector receptor 172 connected to connector base 166. By onlydisconnecting either the connector receptor 172 or the connector insert170, housing 210 can be brought to the surface with connector assemblies140 intact. Further disassembly of connector assembly 140 may beperformed at the surface, preventing damage to components of connectorassembly 140 and allowing reuse of all components.

A method for installing a VIVI around a structure utilizing a ROVincludes engaging at least one receptor engagement slot 160 with atleast one receptor engagement tool and engaging at least one insertengagement slot 160 with at least one insert engagement tool; moving theVIVI to a structure 500; opening the VIVI to fit around the structure500; extending the VIVI around the structure 500; closing the VIVIaround the structure 500; and disengaging the respective engagementslots 160. The method may further comprise the step of locking at leastone receptor assembly to at least one insert assembly. As discussedpreviously, the ROV engagement tools may perform the locking step. Thelocking step may be performed simultaneously with the closing step.

In an alternative embodiment of the VIVI, depicted in FIGS. 9, 10 a, and10 b, housing 210 is preferably manufactured as a single componenthaving a cylindrical shape with a front housing 250 flanked by a firstwing 252 along a first pivot line 242 and by a second wing 254 along asecond pivot line 244. First wing 252 is rotatable in relation to fronthousing 250 along first pivot line 242. Second wing 254 is rotatable inrelation to front housing 250 along second pivot line 244. First wing252 has a first lock edge 232 distal first pivot line 242. Second wing254 has a second lock edge 234 distal second pivot line 244. Alongitudinal opening 230 is defined between front first lock edge 232and second lock edge 234. A plurality of connector assemblies 140 arelocated on first and second wings 252 and 254, proximate first andsecond locking edges 232 and 234.

In the alternative embodiment, a series of openings 246 are providedalong pivot line 242 and pivot line 244. Openings 246, in the embodimentshown, comprise slots and holes extending through housing 210. Openings246 enhance preferential bending of the wings 252 and 254 in relation tofront housing 250 along pivot lines 242 and 244 as aligned openings 246provide increased flexibility of housing 210 at openings 246.

In the alternative embodiment, fins 220 terminate in the area proximatepivot line 242 between front housing 250 and first wing 252 and in thearea proximate pivot line 244 between front housing 250 and second wing254. Continuing to refer to FIG. 9, recess 224 between the terminus 222of fin 220 on front housing 250 and the commencement 226 of fin 220 onsecond wing 254 permits the rotation of wing 254 to an open position.Like recesses on at pivot line 242 permit rotation of first wing 252.

Housing 210 has elastomeric properties and is flexible between fronthousing 250 and first wing 252 and between front housing 250 and secondwing 254 so that first and second wings 252 and 254 may be rotated to anopen position wherein lock edges 232 and 234 are separated, as depictedin FIG. 10 b. With wings 252 and 254 opened, housing 210 may be placedaround structure 500. Inner surface 215 of housing 210 faces outersurface 502 of component 500 when strake 100 is installed.

In the alternative embodiment of housing 210, fins 220 terminate in thearea proximate pivot line 242 between front housing 250 and first wing252 and in the area proximate pivot line 244 between front housing 250and second wing 254. Recess 224 between the terminus 222 of fin 220 onfront housing 250 and the commencement 226 of fin 220 on second wing 254permits the rotation of wing 254 to an open position. Like recesses onat pivot line 242 permit rotation of first wing 252.

The installation of the alternative VIVI found in FIGS. 9, 10 a, and 10b is consistent with the installation of the preferred VIVI. However,first wing 252 and second wing 254 allow the ROV to remain engaged withalignment stub 110 during installation. This is due to the fact thatrotation of first wing 252 and second wing 254 along pivot lines 242 and244 reduces the stress on housing 210. As the ROV may remain engagedwith alignment stub 110, the ROV can assert greater control over VIVI100.

In a separate alternative embodiment (not shown), housing 210 is moldedto provide a reduced cross-sectional area along at least a segment ofpivot lines 242 and 244. As with openings 246, the reducedcross-sectional area along pivot lines 242 and 244 enhance bending alongpivot lines 242 and 244.

In yet another alternative embodiment (not shown), housing 210 isinitially constructed with a distinct front housing 250 and distinctwings 252 and 254. In such embodiment, wings 252 and 254 are attached tofront housing 250 with mechanical hinges at pivot lines 242 and 244 suchthat wings 252 and 254 rotate about pivot lines 242 and 244.

Referring to FIGS. 9, 11, 12, 13, and 14, an alternative connectorassembly 340 is depicted. Connector assembly 340 includes a connectorreceptor assembly 348 and a connector insert assembly 358.

Referring to the receptor assembly 348 depicted in FIG. 12, connectorbase 366 includes a base housing 365 having a front wall 353 and a rearwall 357.

A front opening 359 (seen in FIG. 11) is provided in the front wall 353,the opening 359 extending to rear wall 357. Opening 359 is sized toallow receptor segments 382 and 384 to extend through opening 359 toabut rear wall 357. Upon installation of receptor 372 into base 366, aretainer pin 367 may be inserted through aligned holes 380. A flange 369extends outwardly from receptor 372 intermediate grooved ends 388 and389 and holes 380. Receptor 372, base housing 365 and holes 380 are sostructured and aligned that receptor 372 is fixedly retained onconnector base 366 with base housing 365 intermediate flange 369 andretainer pin 367.

Pin 367 has a grasping loop 373 extending outwardly from pin 367 andbase housing 365 to allow removal of pin 367 by an ROV manipulator tool(not shown).

A rear extension 350 extends outwardly from rear wall 357. Rearextension 350 is provided with an engagement slot 360. Engagement slot360 is sized and structured to allow an ROV manipulator tool (notshown), such as a hook or a solenoid-operated rod to extendtherethrough.

Referring to the insert assembly 358 depicted in FIG. 14, connector base368 includes a base housing 385 having a front wall 383 and a rear wall387.

A front opening 389 (seen in FIG. 11) is provided in the front wall 383,the opening 389 extending to rear wall 387. Opening 389 is sized toallow connector pin 370 to extend through opening 389 to abut rear wall387. Upon installation of connector pin 370 into base 368, a retainerpin 367 may be inserted through hold 380. A flange 377 extends outwardlyfrom connector pin 370 intermediate barbed end 390 and hole 380.Connector pin 370, base housing 385 and hold 380 are so structured andaligned that connector pin 370 is fixedly retained on connector base 368with base housing 385 intermediate flange 377 and retainer pin 367.

Retainer pin 367 has a grasping loop 373 extending outwardly from pin367 and base housing 385 to allow removal of pin 367 by an ROVmanipulator tool (not shown).

A rear extension 350 extends outwardly from rear wall 387. Rearextension 350 is provided with an engagement slot 360. Engagement slot360 is sized and structured to allow an ROV manipulator tool (notshown), such as a hook or a solenoid-operated rod to extendtherethrough.

The connector assembly 340 provides an alternative means for engagingthe connector assembly 340 by an ROV manipulator tool or a diver. Theoperation of connector assembly 340 is consistent with the operation ofconnector assembly 140, providing a like facility for ready disassembly.

The foregoing description of the invention illustrates a preferredembodiment and alternate embodiments thereof. Various changes may bemade in the details of the illustrated construction within the scope ofthe appended claims without departing from the true spirit of theinvention. The present invention should only be limited by the claimsand their equivalents.

1. A method for installing a vortex induced vibration inhibitor around astructure, utilizing a remotely operated vehicle, comprising: anengaging step comprising engaging at least one receptor engagement slotcoupled to at least one receptor assembly with a receptor engagementtool, and at least one insert engagement slot coupled to at least oneinsert assembly with an insert engagement tool, wherein said at leastone receptor assembly and said at least one insert assembly arecontained on a vortex induced vibration inhibitor of a type comprising aflexible, unitarily formed hollow cylindrical housing; a moving stepcomprising moving said vortex induced vibration inhibitor to a structureto be covered; an opening step comprising operating said housing to anopen position; an extending step comprising extending said housingaround said structure; a closing step comprising operating said housingto a closed position; and a disengaging step comprising disengaging eachsaid receptor engagement tool from said corresponding receptorengagement slot, and disengaging each said insert engagement tool fromsaid corresponding insert engagement slot.
 2. The method of claim 1,further comprising: a locking step comprising locking said at least onereceptor assembly to said at least one insert assembly.
 3. A connectorassembly for a vortex induced vibration inhibitor constructed as ahollow housing, said housing having a longitudinal opening defined by afirst locking edge and a second locking edge, said housing operablebetween an open position and a closed position, said first and secondlocking edges separated in said open position and said first lockingedge proximate said second locking edge in said closed position,comprising: a receptor assembly; an insert assembly; said insertassembly disposed at one of said first locking edge and said secondlocking edge; said receptor assembly disposed at the other of said firstlocking edge and said second locking edge; said insert assemblyincluding a connector pin; said receptor assembly including a receptorfor receiving said connector pin; said connector pin having an insertend and a second end; at least one barb proximate said insert end; saidreceptor having a receptor cavity defined by a receptor wall; at leastone groove provided interior of said receptor wall; and said insertassembly and said receptor assembly aligned such that said connector pinis received in said receptor in said housing closed position with saidat least one barb fixedly received in said at least one groove.
 4. Thedevice of claim 3, further comprising: said insert assembly having aninsert housing, a retainer pin opening in said insert housing and aretainer pin; and said connector pin disconnectable from said inserthousing upon removal of said retainer pin from said retainer pinopening.
 5. The device of claim 4, further comprising: said retainer pinhaving a grasping loop.
 6. The device of claim 3, further comprising:said receptor assembly having a receptor, a receptor housing, a retainerpin opening in said receptor and a retainer pin; and said connector pindisconnectable from said receptor housing upon removal of said retainerpin from said retainer pin opening.
 7. The device of claim 6, furthercomprising: said retainer pin having a grasping loop.
 8. The device ofclaim 3, further comprising: said at least one barb comprising aplurality of barbs; and said at least one groove comprising a pluralityof grooves.
 9. The device of claim 3, further comprising: said at leastone barb comprising a plurality of barbs; and said connector pin insertend having a conical insert tip.
 10. The device of claim 3, furthercomprising: said insert assembly further comprising an insert housing;said insert housing having a front wall and a rear wall; an inserthousing cavity extending through said housing front wall to said housingrear wall; and said connector pin extending into said insert housingcavity.
 11. The device of claim 10, further comprising: said inserthousing having a housing retainer pin opening extending laterallythrough at least one wall of said insert housing; and said connector pinhaving a connector retainer pin opening intermediate said insert end andsaid second end.
 12. The device of claim 11 further comprising: saidretainer pin extending through said insert housing retainer pin openingand said connector pin retainer pin opening.
 13. The device of claim 3,further comprising: said insert assembly further comprising an inserthousing; said insert housing having a front wall opening and a rear wallopening, and an insert housing cavity extending therebetween; saidconnector pin extending through said insert housing cavity; saidconnector pin second end extending outside said insert housing; and aconnector pin retainer pin opening provided in said connector pinintermediate said insert housing and said second pin end.
 14. The deviceof claim 13, further comprising: said retainer pin extending throughsaid connector pin retainer pin opening.
 15. The device of claim 14,further comprising: a pin flange intermediate said insert housing andsaid connector pin retainer pin opening.
 16. The device of claim 3,further comprising: said insert assembly further comprising an inserthousing; and an insert engagement slot provided on said insert housing.17. The device of claim 3, further comprising: said receptor assemblyfurther comprising a receptor housing; and a receptor engagement slotprovided on said receptor housing.
 18. The device of claim 3, furthercomprising: said receptor having a receiving end and a receptor secondend; said receptor assembly further comprising a receptor housing; saidreceptor housing having a receptor housing front wall and a housing rearwall; a front wall opening provided in said receptor housing front wall;and said receptor extending through said receptor front wall.
 19. Thedevice of claim 18, further comprising: said receptor housing having areceptor retainer pin opening extending laterally through at least onewall of said receptor housing; said receptor having a retainer pinopening intermediate said receiving end and said second end, and saidreceptor housing retainer pin opening and said receptor retainer pinopening aligned.
 20. The device of claim 19, further comprising: aretainer pin extending through said receptor housing retainer pinopening and said connector receptor retainer pin opening.
 21. The deviceof claim 3, further comprising: said receptor having a receiving end anda receptor second end; said receptor assembly further comprising areceptor housing; said receptor housing having a receptor housing frontwall and a receptor housing rear wall; an opening provided in saidreceptor housing front wall; a receptor housing rear wall openingprovided in said receptor housing rear wall; said receptor extendingthrough said receptor housing front wall opening and said receptorhousing rear wall opening; said receptor second end extending outsidesaid receptor housing; and a receptor retainer pin opening provided insaid receptor intermediate said housing rear wall and said secondreceptor end.
 22. The device of claim 21, further comprising: a retainerpin extending through said retainer pin opening.
 23. The device of claim22, further comprising: said retainer pin having a grasping loop. 24.The device of claim 21, further comprising: said receptor constructed ofat least two receptor wall segments; said two receptor wall segmentsdefining at least in part a hollow cylinder; and said two receptor wallsegments at least partially held in abutting relationship by a retainingsleeve.
 25. The device of claim 24, further comprising: a receptorflange segment extending outwardly from each of said at least tworeceptor wall segments; said receptor flange segments intermediate saidreceiving end and said receptor second end; said retaining sleeve sizedto receive at least two receptor segments; and said retaining sleeveabutting said receptor flange segments.